s'loo (Manx) comes from Manx s’, from Old Irish ís, from Proto-Celtic ɸīssu, from Proto-Indo-European pedsú, from Proto-Indo-European pṓds, from Proto-Indo-European póds, from Proto-Indo-European ped- — to walk, to step; to stumble, to fall.
Ancestry of “s'loo”, step by step
s'loo traces back through two separate lines of ancestry.